Electric cables come in a wide variety of shapes, types of conductors, number of conductors, insulation, and configurations. Electrical cables can be as simple as a single conductor with a simple insulator on the exterior of the conductor, or they can be very complex having multiple conductors of different sizes and different types with varying terminations or exit points along the length. The cabling can also have various termination devices on the ends of the conductors or they can be left bare, depending on the particular application.
Electrical cables of some sort are used in practically every device incorporating any electronics or electronic devices. Cabling is required to tie in the source of electricity to the electronics and to deliver and transfer electronic signals to other electronic device, to gauges, meters, lights or other visual indicators, to allow communications between devices and coordination of activities. Any time any type of electronic signals or current has to be delivered or transferred from one device to another electrical cables are generally in use.
Typically, when there are multiple signals or currents being transmitted between devices in most modern day apparatuses or machines, a custom electrical cable having multiple conductors and multiple terminations are made. Custom made electrical cables are used in automobiles, trucks, airplane, jets, rockets, other types of military apparatuses, computers, televisions, some telephones, stereos, and practically every other device imaginable employing any type of electronics.
In the past electrical cables have been made by several different configurations and methods. Typically, multiple conductors are contained within a sheath or covering. The sheath can be wrapped or molded by several different types of methods known in the art. Molding techniques result in a cable having multiple conductors surrounded by some sort of molding compound. The cable can be in one of several different configurations. The cable can be a flat ribbon, or round in the most common configurations. The multiple conductors can all run parallel to each other or they can be wrapped around each other in some sort of woven pattern, depending on the particular application and types of conductors.
In one instance of the prior art, electrical conductors are woven in a particular pattern such that the primary signal wire has non-signal carrying wires wrapped around it. This provides protection from interference from other signals. The non-signal wires can be current carrying conductors or ground conductors. The woven wires are then surrounded by an insulating material in most instances.
Particular applications having custom cabling often have conductors entering and leaving the cable at several different locations, with each having some sort of termination device. These type of cables are often prepared in some sort of jig designed specifically for the particular application. The wire are installed individually or in particular groups along the jig. Each of the wires or groups are added to the cable at particular locations leaving a sufficient length extending from the cable for a termination device and to enable the termination device to connect to some electrical apparatus. Once all the wires are in place, the cable is wrapped with an insulating material or subjected to a molding process where the cable is covered in the insulating material. The insulating material in the later often completely fills all voids between the wire and completely surrounds the wires forming an exterior insulating material around the cable.
The cabling of the prior art has several disadvantages. Once multiple conductors are included within a cable it is very difficult to make a repair to a single conductor. Typically, the cable outer insulating material has to be removed over a significant length to locate the problem and most be completely removed from end to end if the conductor has to be replaced. If the conductors are included in any sort of woven pattern, a single conductor typically can not be removed or repaired. If the conductor is included in any sort of molded sheath it may be impossible to remove or repair a single conductor without destroying the integrity of the cable.
Another disadvantage is the weight of the insulating material used in making the cable. Weight of the insulating material in some instances may actually exceed the weight of the conductors in the cable. Some applications where electrical cabling is used may be very critical. This is especially true in instances where the apparatus in which the cable is used has some sort of motion or locomotion, such as in automobiles, aircraft, spacecraft, and other military and non-military applications just to name a few.
U.S. Pat. No. 5,331,115 to Ysbrand discloses a molded cabling and a method of production which overcomes the disadvantages noted above. In this patent, a molded woven cabling is produced using injection molding techniques. That is, a plurality of wires or conductors are placed in a mold followed by an injection molding step which forms a harness around the conductors and the molded cable. One of the drawbacks associated with this process is that the conductors or wires used during the injection molding can be adversely affected by the injection molding step.
As such, a need has developed to provide an improved molding technique for making these types of molded cablings. In response to this need, the present invention, in one aspect thereof, provides a new and improved molding method using a preform which can be subsequently removed for insertion of the desired conductors. In another aspect, the present invention provides an improved harness structure for molded cabling.